Inhibitors of glycosyltransferases are to be synthesized and used to demonstrate the presence of glycosyltransferase activity on cell surfaces and to gain evidence of the involvement of glycosyltransferases in intercellular interactions. Methylene (C-glycoside) and thio analogs of alpha-D-glycopyranose 1-phosphates that can be used to prepare methylene and thio analogs of nucleoside diphosphate sugars and polyisoprene phosphate and pyrophosphate sugars are being prepared. These analogs are to be investigated as competitive inhibitors of glycosyltransferases and for their effect on cell proliferation and intercellular adhesion. These investigations are being done to test the hypothesis that cell surface carbohydrate residues are involved in regulating the social behavior of cells.